Perioperative Anticoagulation Management

AF Thrombosis Risk (CHA2DS2-VASc Score)

The score adds one point for each of the following, and two for age 75 or over and for prior stroke, TIA or thromboembolism:

• Congestive heart failure (1 point)
• Hypertension (1)
• Age 75 or over (2)
• Diabetes (1)
• Stroke, TIA or thromboembolism (2)
• Vascular disease (1)
• Age 65-74 (1)
• Female sex (1)

Mechanical Heart Valve Risk

Why mitral is worse. A mechanical mitral valve carries 2-4 times the thrombosis risk of an aortic one, because of its larger surface area, lower flow velocities and left atrial stasis. The risk factors that move an aortic valve into the consider-bridging group are a previous stroke or TIA, AF, heart failure, age over 75 and a hypercoagulable state.

VTE Thrombosis Risk

Warfarin Perioperative Management

LMWH Bridging Protocol

The regimen. Therapeutic-dose enoxaparin, continued after surgery until warfarin has taken over:

• Enoxaparin 1mg/kg subcutaneously twice daily
• Continue LMWH after surgery until the INR is therapeutic (over 2) for at least 2 days
• Monitor anti-Xa levels in renal impairment or obesity
• Consider a UFH infusion if the timing of surgery is uncertain
• Discuss the complex case with haematology

Treat the pre-operative and post-operative halves as separate decisions. They are usually bundled together as "bridging", but the evidence for them differs and so does the risk. BRIDGE tested the whole package in AF and excluded mechanical valves. PERIOP2 randomised 1,471 patients, including mechanical heart valves, specifically to post-operative dalteparin versus placebo and found no thromboembolic benefit: major thromboembolism 1.0% with dalteparin versus 1.2% with placebo, a result consistent in the mechanical-valve subgroup as well as in AF. The post-operative half is also where the bleeding sits, because therapeutic LMWH is being restarted into a fresh surgical wound.

The practical reading. In a genuinely high-risk patient the pre-operative bridge remains defensible, but do not treat post-operative therapeutic LMWH as automatic. Restart it only when haemostasis is secure, accept a later restart in higher-bleeding-risk orthopaedic procedures, and be aware that the trial evidence for that post-operative dose is weaker than most protocols imply, even for a mechanical valve.

Pre-operative Assessment

Confirm the anticoagulation status. Document the date and time of the last dose, check the INR on warfarin or drug levels on a DOAC if they are available, review renal function for DOAC clearance, and confirm the bridging plan if there is one.

Before the day. Check that:

• Anticoagulation held per protocol
• Bridging LMWH stopped at the planned interval
• Platelet function normal if on aspirin or clopidogrel
• Group and screen current
• Plan discussed with anaesthesia if a neuraxial block is intended

On the day. Confirm the patient is fasted and the anticoagulant held, recheck the INR in warfarin patients, and make sure the consent covers the bleeding risks.

Intraoperative Considerations

Anaesthesia coordination. Neuraxial anaesthesia is contraindicated if anticoagulation has not been adequately held, and general anaesthesia is preferred when the coagulation status is uncertain. A spinal is timed by the current neuraxial anticoagulation guidelines.

Technique. Meticulous haemostasis throughout, a tourniquet where applicable, electrocautery for small vessels, bone wax for cancellous bone bleeding and tranexamic acid for major joint surgery.

Blood conservation. Cell salvage for procedures with major blood loss, tranexamic acid 1g IV at induction and 1g at 3 hours, and hypotensive anaesthesia (MAP 60-70) if appropriate.

Haemostasis Strategies

After the tourniquet. Release it before closure, achieve haemostasis under direct vision, and document the blood loss and any transfusion.

Emergency Surgery on Anticoagulation

The patient needs urgent surgery and is anticoagulated. Reversal is specific to the agent:

The balance. The bleeding risk of operating is weighed against the thrombosis risk of reversing, and the case is discussed with haematology.

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The Anticoagulated Hip Fracture - a Time Target, Not an Emergency Reversal

The commonest version of this problem in orthopaedics is not a bleeding emergency but a clock. Hip fracture surgery is targeted within 36 to 48 hours because delay increases mortality, and an anticoagulant is one of the commonest avoidable reasons that target is missed: the patient is admitted, the drug is noted, and everyone waits for it to wear off.

Waiting is the error. The approach differs from true emergency reversal above:

• Warfarin - reverse early and deliberately with vitamin K so the INR falls in time to operate within the target, rather than watching the INR drift down over days. Reserve PCC for a genuine emergency or when the operation cannot wait for vitamin K to work. Restart warfarin once haemostasis is secure.
• DOACs - stop, and time surgery to the drug, the last dose and the renal function, typically 24 to 48 hours. Specific reversal (idarucizumab, andexanet alfa) is for the case that truly cannot wait, not for routine scheduling.
• Aspirin and clopidogrel - generally do not stop, and do not delay for them. Manage bleeding with tranexamic acid and, rarely, platelet transfusion.
• Do not bridge with LMWH when surgery is early and anticoagulation will be restarted promptly: bridging adds bleeding risk without closing a meaningful thrombotic gap.

Involve haematology and anaesthesia early for the complex case, and confirm both the renal function and the indication for anticoagulation, since a mechanical valve or recent VTE changes the calculus entirely.

Suspected Spinal Epidural Haematoma

Recognition. Back pain, progressive weakness, a sensory level or urinary retention within 24-72h of a neuraxial procedure.

Management. An urgent MRI to confirm the diagnosis, immediate neurosurgical referral, and decompressive laminectomy within the 8-hour window from symptom onset. The outcome depends on the neurology before surgery and the time to decompression, and is best when decompression comes before complete paralysis.

Anticoagulation Restart Timing

The decision. The interval is set by the procedure's bleeding-risk category; within it, the restart is judged on the adequacy of haemostasis (drain output, the wound), the thrombotic risk against the bleeding risk, the timing of neuraxial catheter removal, and haematology input for the complex case. In the very highest-risk settings, intracranial surgery among them, the restart is delayed and individualised. Warfarin takes days to take effect once it is restarted.

VTE Prophylaxis Protocol

Mechanical. Graduated compression stockings, intermittent pneumatic compression devices and early mobilisation.

Pharmacological. Usually delayed until haemostasis is assured, at 12-24 hours. The choice is enoxaparin 40mg daily or rivaroxaban 10mg daily, for 14 days after TKA and 28-35 days after THA.

Higher-risk situations. A prior VTE calls for extended prophylaxis of 4-6 weeks, active cancer favours LMWH over a DOAC, and the immobile patient continues until fully mobile.

Postoperative Monitoring

Clinical. The wound for haematoma, drain output if a drain is present, hypotension or tachycardia as signs of bleeding, and neurological status after a neuraxial block.

Laboratory. FBC on day 1-2, the INR on warfarin (target 2-3 for most indications), and renal function on a DOAC.

Red flags. Escalate for:

• Drain output over 500ml in 4 hours
• An expanding wound haematoma
• Hb drop over 20 g/L
• Neurological change after spinal surgery

Bleeding Outcomes

Major bleeding is defined by any of:

• Hb drop of 20 g/L or more
• Transfusion of 2 units or more
• Bleeding at a critical site
• Reoperation for bleeding
• Fatal bleeding

Who bleeds. Inadequate drug cessation, renal impairment with DOAC accumulation, concurrent antiplatelet therapy, and complex or revision surgery.

Thrombotic Outcomes

The events. Stroke or TIA in the AF patient, DVT or PE in the patient with a VTE history, and valve thrombosis with a mechanical valve. Prolonged interruption of anticoagulation, immobility after surgery, malignancy and a hypercoagulable state raise the risk.

Optimal Management Outcomes

What the evidence delivers. BRIDGE removed routine bridging for low-to-moderate-risk AF patients and PAUSE showed standardised DOAC cessation to be safe and effective; bleeding fell without an increase in thrombosis. With optimal management, major bleeding is under 2%, thromboembolism under 1% with appropriate VTE prophylaxis, and reoperation for bleeding under 1%.

Keys to success. Multidisciplinary planning between surgeon, anaesthetist and haematologist, standardised protocols, patient education and compliance, and appropriate timing of the restart.